Follow below narrow down and troubleshooting:

1. Register untransferred clip into the Bin

Use [Add to Bin] instead of [Add and trensfer to Bin] then confirm if registered clip is online. If it is online, try to place it onto the timeline and confirm that it is also online in the timeline.

2. Confirm the file path

Confirm if file path of transferred clip is under project location. Switch Bin view mode to icon view and confirm the file path in ‘File Name’ pane.

3. Copy a file to local drive before registration

Copy a file that you want to use to local drive then register it in the Bin. And confirm that it is also online in the timeline.